f.3 specific latent heat問題---------急用

wai yan

2006-10-22 2:33 am

0.5kg of ice at 0℃ is mixed with 1kg of water at 20℃.Assume that there is no heat transfer betweenthe mixture and the surroundings.Find the final temperature of the mixture.

ans=0℃

請加以解釋及提供計此問題的formula........急用.plz

回答 (1)

用戶122907

2006-10-28 11:55 am

✔ 最佳答案

Specific Latent of water:
334 000 J/kg

Energy required for ice to change the state + Energy required for water to raise till a certain temperature = Energy required for water to decrease a certain temperature
m1l + m1c1△T1 = m2c2△T2

The following T(s) represent the Final Temperature

0.5*334000 + 0.5*4200*(T-0) = 1*4200*(20-T)
167000 + 2100 T = 84000 - 4200T
T = -13.2℃

However, the temperature cannot be under 0℃, as ice is 0℃.
That means, the energy of the 20℃ water is not enough to melt all the ice
∴ Final Temperature is 0℃

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